Short answer
Use a short-term test kit in the lowest lived-in level of your home, or hire a qualified tester: close windows and doors 12 hours before, set the device at least 20 inches off the floor away from drafts, leave it at least 48 hours, then mail it to the lab. A high result gets a follow-up test.
Next step: pick the right test for your home. Which test to use
The quickest way to test is with a
Keep
What to do next: get a kit or book a tester this week, and when the result comes back, read it against the testing steps below or with the interpreter.
Step by step · 1 min read
Step 1 of 7:
Get a test
Low-cost do-it-yourself kits come by mail and from hardware stores and other retailers, and some state radon programs and local health departments hand out free ones. Use a device from a qualified laboratory.
Step 2 of 7:
Close the house
For a test of 2 to 4 days, keep windows and outside doors closed for at least 12 hours before you start and for the whole test, apart from normal coming and going.
Step 3 of 7:
Place the device
Put it in the lowest lived-in level, in a room used regularly but not the kitchen or bathroom, at least 20 inches above the floor, away from drafts, high heat, high humidity and exterior walls.
Step 4 of 7:
Start the test and note the time
Follow the kit's instructions and write down the start date and time.
Step 5 of 7:
Leave it alone
Leave the kit in place for as long as the package says, and never less than 48 hours; some devices need longer.
Step 6 of 7:
Stop, seal and mail
Write down the stop date and time, reseal the package and send it to the lab right away.
Step 7 of 7:
Read the result
Results come back within a few days or weeks. Use the decision steps below, or the radon level interpreter.
In a picture · 1 min read
| Test | How long it runs | What it is for |
|---|---|---|
| Short-term test | Stays in the home from 2 to 90 days, depending on the device, and for a minimum of 48 hours. | A faster screening result. Because radon levels vary from day to day and season to season, it is less likely than a long-term test to tell you the year-round average. |
| Long-term test | Stays in the home for more than 90 days. | It is more likely than a short-term test to tell you the home's year-round average radon level. |
| Continuous monitor | Logs readings for the whole test, run as a short-term or a long-term test under the same durations in EPA guidance. | Logs a graph over time, so you can see trends and spot anomalies rather than a single number. |
A
At a glance · 1 min read
| Do | Do not |
|---|---|
| Test the lowest lived-in level: the basement if it is used, otherwise the first floor | Test in a kitchen, bathroom, laundry room or furnace room |
| Use a room people use regularly, such as a living room, den or bedroom | Test in a closet, stairway, hallway or crawl space |
| Raise it at least 20 inches off the floor; about three feet up in the middle of the room also works | Place it near drafts, high heat, high humidity or exterior walls |
| In a multi-unit building, test the lowest level within your unit | Leave it anywhere it could be moved or disturbed |
For a home sale, the test goes in the lowest level that could be used regularly, finished or not, because a buyer may live lower in the house than the seller does. More on placement is in where should a radon test be placed.
At a glance · 1 min read
A radon test measures the house as it normally sits closed up.
| Allowed | Avoid |
|---|---|
| Normal coming and going through outside doors | Leaving windows or doors open |
| Heating and air conditioning fans that recirculate air | Fans or other machines that bring in air from outside |
| Small exhaust fans for short periods, and a radon system's own fan | Tests of just 2 or 3 days during unusually severe storms or high winds |
| Living in the house as usual | Moving or disturbing the device |
Testing done wrong can give an inaccurate result and mean testing again, and interfering with the device or with closed-house conditions can invalidate the result and is illegal in some states. See can a radon test be manipulated.
In a picture · 1 min read
1Step 1: Take a short-term test.
2Step 2: Follow up with either a long-term test or a second short-term test.
3Step 3: Decide whether to fix your home.
If the first result is high, the next step is a follow-up test: long-term for a better picture of the year-round average, or a second short-term test if you need an answer quickly. If the first result is more than twice the 4
Home sales use three short-term options instead, each with steps against interference: see the radon testing guide.
Questions · 1 min read
If the basement is lived in or used regularly, that is where the test goes. Place the device in a room used regularly, at least 20 inches above the floor, away from the furnace room, laundry and exterior walls, with the house closed up.
Passive devices, such as charcoal canisters and alpha-track detectors, sit in the air for a set time and then go to a laboratory. Active devices, continuous monitors, measure and record radon themselves, and many produce a report that shows unusual swings during the test.
Not during a short-term test. Keep windows and outside doors closed as much as possible, and for a 2- to 4-day test close them at least 12 hours before the start as well.
At least 48 hours, and some devices need longer, such as a 7-day charcoal canister. Short-term tests stay 2 to 90 days and long-term tests more than 90 days. See how long a radon test takes.
Hardware and home improvement stores, mail order, state radon programs, local or county health departments and some American Lung Association offices; your state may offer free or discounted kits. See free radon test kits.
By lowering the radon, not the reading. A test that is interfered with can be thrown out. If the level is high, a mitigation system lowers it; see how to reduce radon.
How a radon test works, who can run one, and how to read the number it gives you.
How a professional radon test works, what it proves and whether it is worth it.
Read the guideWhat counts as high and how to bring them down.
Read the guideEPA's action level, WHO's reference level and what counts as acceptable.
Read the guide